A sample of tap water from the Japanese capital shows a tiny level of radioactive iodine after an earthquake and tsunami damaged a nuclear power plant 240 km (150 miles) north of Tokyo, the government said on Saturday.

The sample contained 1.5 becquerals per kg of iodine 131, well below the tolerable limit for food and drink of 300 becquerals per kg, the government added.

Jiji news agency said the presence of radioactive iodine in Tokyo tap water was rare.